ZHAO Wenyu, ZHANG Qingjie

（State Key Laboratory of Advanced Technology for Materials Synthes is and Proces s ing, Wuhan Univers ity of Technology）

Abstract: An optimized sol - gel proces s for preparing the citrate precursor of BaCoTiFe₁₀O₁₉ was presented in the paper. Crys tallization proces s of Co - Ti subs tituted M- type barium ferrite nanoparticles was inves tigated by XRD and TEM. The results show that the pretreatment method through coprecipitation proces s to eliminate Cl - anions in the citrate sol of BaCoTiFe₁₀O₁₉ can not only greatly improve the s tability of the sol but also completely prevent the formation of α- Fe₂O₃ and BaFe₂O₄ during the whole crys tallization of BaCoTiFe₁₀O₁₉ nanopartilces . BaCoTiFe₁₀O₁₉ nanopartilces formed at 700~900℃ holding for 2 h and at 900℃ holding for 0~2 h are in fact metas table clus ters of atoms with certain internal relations , and the lattice parameters and the cell volume shrank as the temperature rose or the holding time increased. The optimal heat treatment condition for fabricating s ingle - phase BaCoTiFe₁₀O₁₉ nanoparticles with s table s tructure and in size 50- 65nm is at 900℃ holding for 2 h.

Keywords: M- type barium ferrite, nanoparticle, crys tals tructure